Small arm



July 26, 1927. 1,637,233

G. NORMAN SMALL ARM Filed Nov. 17, 1926 2 Sheets-Sheet 2 F1 CL4-w P? 50la ATTR/VEY Patented .lilly 26, 1927.

Biani-inenten, Ei'ieLAivD, Assreivoii 'ro THE' suenen NORMAN, or si/iam.HEATH;

isaiasi r s i Yes BIRIVINGHAIVI SJIALL ARMS VCOMPANY LMITED, OFBIRIVIINGHAM, ENGLAND.

SMALL ARM.

Application filed November 17, 1926, Serial No. 148,953, andY in GreatBritain July 9, 1925.

This invention relates to improvements in small arms, whether of theautomatic or semi-automatic types, embodying bolts or Y breech closureswhich have a combined rotary. and reciprocating movement, and whereinthe receiver and bolt are provided with locking abutment-s inclined atsuoli anY angle to the line of breech pressure as to offer sufficientresistance during the explosion to maintain the closure of the breechbut at the saine time permit the partial rotation of the bolt to releasethe locking abutinents thereon from engagement with lock- 'ingabutments'in the receiver.

An object of the invention is to provide improved means for effectingthe rotary lock ingY movement of the breech boit. A further object is toprovide means whereby the opening in the receiver is covered when thebolt is inits forward or closed position, the said means being furtheradapted to permit of Ythe manual operation of the gun. Another Yobjectis to dispense with the open slots or gaps in the receiver or breechbody which are usually employed to control reciprocat-V ing` movementand to effect rotary movement of the breech bolt, and thereby7 excludedust and foreignA matter from the breech mecha- Vnism. 3o y According tothe invention the initial rotary inoveinent'of the breech bolt or ClohsureV to bring the locking abutments thereon into engagement withlocking abutments in the'receiver is eected by means of the engagementof projection on the bolt with a cam groove in the-receiver when thebolt reaches the inner end of its longitudinal reciprocating movement,and the iinal rotary right angle to the latter.

locking movement is effected by the engagementrof hel-ical cam grooveson the inner or forward end of the breech bolt with a nut or threadedsleeve attached to the under side of a longitudinally slidable coverplate mounted on the upper side of the receiver, said cover plate beingadapted to completely overspread the mouth of the receiver when thebreech mechanism is in its lclosed position.

, The invention also provides means for assisting the rotary lockingmovement of lthe breech bolt, comprising a compression spring interposedbetween the threaded sleeve or nut which engages the forward end of thebreechrbolt, and a shoulder formed on the said bolt.

. line 3 3,

thc breech bolt. y

The invention further provides means whereby the bolt vlocking spring isheld in compression and the locking abutinents on the breech bolt areheld in alignment with guide lugs on the nut or threaded sleeve attachedto the sliding cover plate `during their engagement with slots orsplines in the receiver, during the longitudinal travel of the breechbolt, the said means comprising steps formed in the helical grooves onthe end of the breech bolt which are arranged to move into enoagenientwith circumferentially disposed faces formed in the screw thread i Y ofthe aforesaid sleeve, inthe rotary openin g movement of the bolt.

The invention further contemplates the provision `of means to effect theopening movement of the breech mechanismv by hand.

ln order that Vthe invention may be clearly understood and readilycarried into practical effect, I will describe samev more fully withreference to the accompanying drawings, in which :f

Figure 1 is a longitudinal vertical section of an yautomatic small .armconstructed in `accordance with and embodying the features of thisinvention.`

Figure 2. is a part sectional plan View.

Figure 3 is a transverse section-taken on Figure l. .i

Figure l isran end' view' of the cover rplate and the nut or threadedsleeve associated therewith..

Figure la is a longitudinal sectional view vof the parts shown in Figurel.

Figure 5 is aside and Figure 5a is a view similar to Figure 5 at Figure5b is'an end view of the breech bolt.

F igureG is an end view and aside elevation of the breech bolt lockingspring.

Figure 7 is a view partly in section and partly in elevation, of thecover plate and which the receiver or body is formed in two parts, theforward part l `being attached at its front end to the gun barrel 2, andhaving an end elevation of its rear end provided with internalv screwthreads to receive a locking sleeve 3 and the rearward portion-,4t ofthe' receiver. The

breech bolt in order' to bring'rits locking abutments y(3 intoengagement With abutments 9 in the vlocking sleeve Xed inthevforvvardpart-1 of` the receiver. I Said angular portion grooves 41() inwhichVare formed 'circumferf of .the said cam'slot 8 is parallel to the in-VAclned'faces of the lockingabutment's 16 and"A 97 and is adapted tocontrol theiinal rotary locking movement of the 'breechI bolt.

vThe` forward end ofthe'breech belt.'V 5V is provided* With'screwthreads'or helical cam n Yentially disposed flat faces or steps 11, the

' said screwed end engaging With a nut or in- .ternally screw-threadedsleevef12 attached in vthe manner hereafter describedto the undersidefront end of va cover plate 13 for the, '.mouth of the; receiver, whichis j slidably mounted on Vthe lupper side ofthe," receiver and providedWith ars'uitableV handle 14 for moving itto effect the opening ofthebreech mechanisrnby hand. Between' the rearend Y @ofthe threaded sleeve'12 mountedy on' the der lirformed on-Vthev latter, ris interposed a-Lfront end-of the breech bolt 5 .anda shouliat section spiral springv16.

. The'` breechbolt 45 risi ofgholloyv or tubular formation and-'Withinsaid hollow portion Ward Vendnaryiring pinl18 invvhijch-is formed 20ymounted in the'breechbolt 5 and adapted to limit .and"control, inknownmanner, the movement of .rthezsaid firing pin 18. In the Beforeassembling thebreech bolt 5in the breech 'bodyfor receiver, the nut -orthreaded j sleeve 12 is mounted thereon, and thebolt is partiallyrotated vto bring. itscircumferential- Vly disposed flat faces or steps11 into engage- A ment With corresponding steps-or flat faces.A 21,formed by cutting circular groovesin the interior of Vsaid sleeve 12to"inte'rsect thev screw threads thereof.' YThus. theqspring "16 on thebreech boltis held in itscompressed position, and .their locking.abutments 6 on i' the *boltv 5 vare Yretained in alignment 'withguidelugs 22 onvthe 'said sleeve 12. v`The cover plate `13 .is vthenslid into its forward position over. thevmouth of the receiver.` Theassembled breech bolt 5 and its return spring Yare then passedinto theVbreech kbody o rV receiver VWithvth'e guide lugs 22 on thethreadedasleeve 12 and the lccking abutments 6 on the bolt Sengagingvvith longitudinal "guide 50 grooves Vor "splines'23tFig 3) in thebreech ,Y

bedy The cover plate 13 is then Withdrawn 'Y a short distance'bymeans ofits handle 14,

in order to ,bring alug. ,211 depending from its 'under-'iside'. atitsfront end into alignment VVWitha Hat rface yformed on the upperv sideof the'nutv or threaded sleeve 12imountand the-saidfparts'arethenvlocked by 'any .fsuitableinf'eansv VrSuchlocking may be effectedlon the front' end of they breech bolt '5, c

Yspending groove '27 formed in the upper vside `of the threaded sleeve12, together vvith "screw-threaded pin 28y extending'e'throughthejlug'24'of the Ysaid cover plateandadapt- Y ed toff'enteraradialholevinV thelsleeve 12. The pin 2S may be providedV at Yits outer endvrWith la handle orrlever 29 vvhereby4 it may Y vbe vnotated to causeitsinner end to engage :with or Vdisengage from the sleeve"12.V Thehandle'or lever'29of the said attachment pin ispreferably of a springycharacter. and pro-Y videdavitli'a nib or projection 30 adapted'to Y4V,The Voperation 1s as follows :i-VVhenfthei gun-v is'ired theinclinationofthe abutting:V l

"su'r'facesof the locking abutmentsVV 6 and 9 is suchI as tooer;Ysufficient resistance y(during Y theeXplosion tofmaintain the` closureof Vthe is mounted a striker 17YV carrying at its for# bolt, yet,` inAknown manner permitting the rotation of the bolt 5 by the? breechpressure7 so that the locking abutments 6 on vsaidlbolt are'fmoved intoalignment withl the longitu i i Withithe angularpart front end ofthe camv groove v8v in thexreceiver causes the fiat faces or steps 11 in thehelical cam grooves 10 of VYthe breech bolt 5 to engage -with the flatVfaces 21 formed by the in ternal groovesin the nut or sleeve 12 carriedby the sliding cover plate 13, thelatterrhaving been moved tothe `re- Yquired position by the rotation of the breech bolt 5 and consequentrearwardmovement. ofV

the sleeve 12.y At the same time the locking spring 16hasbeen-Acompressed, as shown'in `'Figure V7, 1 The continued breechpressure Ycauses the Abolt 5 to travel rearwardly, during.

which movement the extractionand e'ection I return spring V32 iscompressed to effect the fof the spent cartridge is effected and t e'bolt f I:tr-3373.233

During the return movement. of the breech bolt 5, under the action ofits spring 32, the

sear 33 of the trigger mechanism engages. the lug or bent 34k action of.the said spring is thus arrested, but due to its momentum the'breechbolt 5 continues its closing movement, and, when it is near the end ofits abutments 6 have reached the end of the longitudinal guide grooves23 in the receiver the lug or projection 7 in the rear end of the bolt 5engages with the curved part of its cam groove 8 in thev receiver, andimparts a rotating movement to the bolt 5 which brings its lockingabutments 6 into alignment or first engagement with locking abutments 9in the receiver, and also` moves the fiat faces or steps 11 in thehelical cam grooves 10 on the bolt 5 out of engagement with-the flatfaces 2l in the screw thread of the nut or sleeve 12 on the slidingcover plate 13, thus releasing the bolt locking 'spring 16 which then,through the nut or sleeve 12 and pin 28, eX- erts its pressure on thesliding cover plate -13 and effects the final turning movement, thuslocking the breech bolt.

Having fully described my invention, what I desire to claim and secureby Letters Patent is l. In a firearm, a receiver having internal lockingabutments, a locking bolt movable longitudinally in said receiver andhaving peripheral locking abutments, said locking bolt being alsorotatable to cause engagement of its locking abutments with the lockingabutments of the receiver, said bolt also having a peripheral projectionand said receiver having a cam groove cooperative with said projectionto cause rotary movement of the bolt during a part of the longitudinalmovement of the latter, means tending to move said locking boltforwardly, a member longitudinally movable in said receiver andassociated with said bolt, a spring associated with said member and saidbolt and tending to move said member and bolt in opposite directions,said member and said bolt having interengaging means adapted, during therearward movement of the bolt under the influence of a liringrecoil andconsequent rotary movement of the bolt by engagement of its projectionwith said cam groove, to move said member toward the rear end of saidbolt and compress said spring and lock said membei' to said bolt and,when said bolt is moved forwardly, to unlock said member from said boltand permit said spring to expand.

2. In a firearm, a. receiver having internal locking abutments, alocking bolt rotatable and longitudinally movable in said receiver, saidlocking bolt having peripheral locking abutments and a peripheralprojection, said receiver having a cam groove in which said peripheralprojection moves and adapt-ed, when said bolt is moved longitudinally,to

of the striker 17, andv thev travel and its lockingl impart rotary.motion thereto` and cause its locking abutments to engage with thelocking abutments of the receiver, a spring tending to -move saidlocking bolt forwardly, a sleeve surrounding said locking bolt andlongitudinally slidable in the receiver, a second lspring associatedwith said sleeve and said bolt and tending to move said sleeve and saidbolt in opposite directions, said sleeve and said bolt havinginterengaging helical means adapted, when said bolt is moved rearwardlyby a firingv recoil and isv causedte rotate'by movement ,of itsprojection in said cam groove, to move said sleeve towardl the rear endof said bolt to compress said second spring and, when :said Vbolt ismoved for.- wardly by said first spring, topermit said second spring tomove said sleeve towardk the forward end ofthe receiver and impart afinal forward o1V bolt. n

3. A firearm according toV claim .k1-wherein the receiver has a mouthand a cover plate is associated with the member which is longitudinallymovable in the receiverand is movable into position to close said mouthduring the forward or closing movement of the breech bolt.

et. A firearm according to claim 1 wherein the longitudinally movablemember has peripheral guide lugs and the receiver has internallongitudinally extending guideways in which said guide lugs are movableand' in which the locking abutments of the bolt are held out ofengagement with the locking abutments of the receiver during part of thelongitudinal movement of the bol In a firearm, a receiver having a mouthand internal locking abutments, a locking bolt rotatable andlongitudinally movable in said receiver, said loclingbolt having lockingabutments and a projection on its periphery and said receiver having acam groove in which said projection moves and which is adapted, at theend of the forward longitudinal movement of the bolt, to impart rotarymovement to the bolt and cause its locking abutments to engage with thelocking abutments of the receiver and, at the beginning of the rearwardlongitudinal movement of the bolt, to impart a reverse rotary movementto said bolt and cause the disengagement of said locking abutments, asleeve on said bolt and longitudinally movable relatively to saidreceiver and said bolt but locked against rotation, means for movingsaid bolt forwardly, a spring associated with said bolt and sleeve andtending to move the same longitudinally of said receiver in oppositedirections, said bolt and said sleeve having interengaging meansadapted, when said bolt is moved longitudinally in one direction, tomove said sleeve in the same direction and compress said spring and holdit in compres'- sion, and, when said bolt is moved longitudiclosingmovement tothe f l fcarriedlbyitliesle'evevanda screw :having a YVspring lever at its upper end and Working in 1 a; Vvertical threadedopeningv through' thel Vcover-11plate and lug engages'the sleeve,thespriiig'for imparting ai forward nioveinent to Y -Said sleevel and aylinal forwvaidclosing niovement to said bolt, a cover plate niovableover 'the lniouth of 'the4 receiver, and'ineansfconnectin'g said coverplaterto saidV sleeve.

tlieV .means or'connecting ,the cover plate to the sleeve comprises alug'ffcairiedV by fthey :underside of thecover' plate andhaving an:undercut yrib engaging a carried by the sleeve and a screwworking incomplemental rib 1a' verticaly threaded opening through'- said v tl'iesleeve'rconipiises'a lng carriedr by the un@ Y derside of thekcoverplate and having an cover plate and lug engagee the sleeve. Y '517.Aflirearm according to claiin wherein the nieanS for connecting thecover plate'to undercut vrib engaging Val VVcomplemental 'i'ib fend ofsaid spring lever. being engageable Awitha depression inthe receiver forholding ySaid screwlagainstirotation. Y

- 8. InV aiirearm, a receiver having-amoutli and `provided with aV camgroove inclined atlite forward eiidat an anglev toits length 5 and also;with' internal locking. abutments, rotatably and longitudinally l'locking f `bolt movable-in said receiver, ysaid lockingV bolt groovevand also V having .locking abutnients inf theinclined portion 'of theVcain groove Vduring the longitudinal movement, of the bolt to engage,Witliand disengage Vfrom the locking abutniente of :the receiver',arcover Y in the'opposite directionrbyrarring recoilrand is, given arotary nioveinentbyr engagement of its pro-- ject-ion in' theV inclinedportion ofv the cam mouth. Y

' f In testimony whereof liave` hereunto set iny hand. I

GEORGE NORMAN.

vei` sai d mouth Y and l having a projection movable iiiv said earn' Ycaused by the inoveinent of Said projection fn. 1 A firearm according toclaiin 5 wherein 'said covervplate, said zslidable means and said" boltjhaving interengaging Y' means adapted,' ivhensaid boltis nio'vedkrone-direction, lto v'inoveVsaidcover platexo Y l vlock saidslidableineansto the bolt,a-iid, *when saidzbolt is moved

